Cell Biology

Peroxisome Biogenesis

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Science  28 Jan 2000:
Vol. 287, Issue 5453, pp. 549
DOI: 10.1126/science.287.5453.549b

Peroxisomes are a class of vesicular organelles involved in lipid and drug metabolism. The number of peroxisomes in a cell can be increased when cells are exposed to certain chemicals, for example, oleic acid. Peroxisome biogenesis disorders, such as Zellweger syndrome, neonatal adrenoleukodystrophy, and infantile Refsum syndrome, are lethal genetic disorders that cause severe mental retardation. How peroxisomes form has not been well understood—fusion of small vesicles is one possibility, but the existence and characteristics of these precursor vesicles have not been established.

Titorenko et al. have now examined the formation of peroxisomes in the yeast Yarrowia lipolytica in detail and describe six vesicular intermediates in the production process that are linked by vesicular fusion and vesicular maturation through protein import. They go on to describe the fusion of the first two intermediates in the pathway in a cell-free reaction that requires cytosol and energy in the form of adenosine triphosphate (ATP). Furthermore, they provide evidence for a role for two members of the AAA family of membrane-associated adenosine triphosphatases in the fusion reaction itself. Why peroxisome biogenesis requires so many distinct intermediates is unclear, and the source of the precursor vesicles remains obscure. However, the molecular dissection of the assembly process will enhance our understanding of the basic cell biology of these organelles and may help in defining and circumventing the defects in peroxisomal biogenesis disorders.—SMH

J. Cell Biol.148, 29 (2000).

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